There are questions about the corn height this year being shorter than normal for corn planted in April. This appears to be the case due to at least 3 factors:
1) Corn planted early is normally shorter than corn planted late due to a reaction to day length being shorter, early in the growing period.
2) Corn height was reduced due to suboptimal growing conditions during early development due to excess water and cooler temperatures in late April and parts of May.
3) Periods of excessive heat in early to mid June correlated with drier conditions and the corn plants often were unable to maximize growth as significant leaf rolling occurred and limited photosynthesis and moisture reduced cell elongation.
It may be interesting to look at the height as an indicator of potential yield, but chances are that it's minor compared to the water relations and temperature during pollination. For those farmers who missed the rains recently, we need to be concerned that the plants recover overnight and silk timely and, for now, be relatively unconcerned about plant height.